The present invention relates to apparatus for reclining a vehicle seat designed to increase the strength and reduce the size.
A patent document 1 (JP2008-18108A) discloses a vehicle seat reclining apparatus including a frame member connected with one of a seat cushion and a seat back pivotally connected with the seat cushion, a cover or lid member which is connected with the other of the seat cushion and seat back and which is arranged to rotate relative to the frame member, and a regulating member regulating axial movement of the cover member relative to the frame member. This seat reclining apparatus further includes a lock tooth member for locking and unlocking the relative rotation of the cover member relative to the frame member, and a cam member for shifting the lock tooth member to a lock position or an unlock position.
In the case of vehicle collision, a great force is applied to rotate the seat back violently toward the front of the vehicle, relative to the seat cushion. Therefore, the seat reclining mechanism is required to have a sufficient strength. In order to increase the strength, it is necessary to increase the teeth of internal gear (module) capable of engaging with the lock tooth member by increasing the outside diameter of the cover member or to increase the wall thickness of the lock tooth member. In the case of the increase of the wall thickness of the lock tooth member, it is necessary to increase the axial length of a cylindrical portion of an outer circumferential portion of the cover member. When the cylindrical portion of the cover member is formed by drawing and the outer circumferential portion of the cover member is shaped like a flange in order to increase the axial length of the cylindrical portion without increasing the outside diameter of the cover member as in the patent document 1, it is further required to increase the axial length of the regulating member for regulating the axial movement of the cover member. A patent document 2 (JP2004-121508A) discloses similar vehicle seat reclining apparatus.